Although blackboards usage has it's charm, its long term use can have negative side-effects on one's health ending with symptoms not dissimilar to ones manifest

Although blackboards usage has it's charm, its long term use can have negative side-effects on one's health ending with symptoms not dissimilar to ones manifesting in coal miners. https://www.degruyter.com/downloadpdf/j/jim.2017.2.issue-4/jim-2017-0089/jim-2017-0089.pdf https://www.degruyter.com/downloadpdf/j/jim.2017.2.issue-4/j...